The information capacity of a single photon

Abstract

Quantum states of light are the obvious choice for communicating quantum information. To date, encoding information into the polarisation states of single photons has been widely used as these states form an natural closed two state qubit. However, photons are able to encode much more -- in principle infinite -- information via the continuous spatio-temporal degrees of freedom. Here we consider the information capacity of an optical quantum channel, such as an optical fibre, where a spectrally encoded single photon is the means of communication. We use the Holevo bound to calculate an upper bound on the channel capacity, and relate this to the spectral encoding basis and the spectral properties of the channel. Further, we derive analytic bounds on the capacity of such channels, and in the case of a symmetric two-state encoding calculate the exact capacity of the corresponding channel.

6 pages, 4 figures

References in corpus (6)

• Quantum Capacities of Bosonic Channels
• Generation and characterization of multimode quantum frequency combs
• Spectral structure and decompositions of optical states, and their applications
• On Secure Quantum Key Distribution Using Continuous Variables of Single Photons
• Quantum entanglement enhances the capacity of bosonic channels with memory
• Coherent control of single photon states

Cited by in corpus (2)

• Pulse shaping using dispersion-engineered difference frequency generation
• Enhanced transmission capacity for laser communication at the single-photon level using the multi-channel frequency coding scheme